This disclosure relates to powder metallurgy processes and, more particularly, making a bimetallic composite.
Aerospace or other types of parts may be designed for operating in severe environments. In this regard, the parts may be fabricated from materials, such as superalloys, that have excellent stability in the given environment. In some cases, the parts may be bimetallic to obtain beneficial properties of multiple alloys. As an example, gas turbine engine rotors and blisks, may include a core formed from a first alloy and a protective coating formed from another alloy. The core may provide desirable mechanical properties, while the coating may provide resistance to the substances in the surrounding environment, for example.
Powder metallurgy has been used with the technique of hot isostatic pressing (“HIP”) to fabricate bimetallic parts by consolidating a powdered alloy in a sacrificial tool to form the core. The interior of the tool may be directly plasma-coated with the alloy of the protective coating alloy. Upon consolidation in the HIP process, the alloy on the tool bonds to the core. When the tool is removed, the alloy remains on the core as the protective coating.